Dear all,

I am asking about the pressure output of the gas turbine compressor. is-it absolute pressure transmitter or pressure gauge transmitter?

in GE gas turbine and Siemens gas turbine.

 

Generally gas turbine (with reference to 9FA frame) compressor discharge pressure is measured with the help of 3 transmitters (Tag no:96 CA- 1A/1B/1C, generally Drux make) these are gauge pressure transmitters. HP tapping is taking from compressor last stage discharge pressure and LP tapping is leaving to atmosphere. by this we can measure the compressor discharge pressure. SO, these 3 transmitters are gauge pressure transmitters...

and this transmitter is used for determine the compressor pressure ratio with the help of other pressure transmitters like inlet dp, barometric pt, and compressor suction pt. also. Compressor pressure transmitters HP tapping is also used to determine the D5, PM1, PM4 (Tag no: 96GN-1/2/3) gas manifold pressure, for these transmitters. HP tapping is taken from gas manifolds and LP tapping is taken from Compressor discharge. During gas turbine start up until purging timer competed, gas valves are not open, but compressor is develop the up to 7 bar due tp. thus these GN Gas pressure transmitters are values are in negative reading. And generally only barometric pressure transmitters are absolute pressure transmitters having only single tapping leave to the atmosphere is measure the atmospheric pressure.

 

Gas Turbine Siemens V 94.2 has one pressure transmitter (MBA21CP001) at compressor discharge which measures gauge pressure where low side is open to atmosphere and high side is taken from last stage of compressor.

regards
ashiq